use std::f64::consts::PI;

/*mod nation {
    pub mod government {
        pub fn govern() {
            println!("组织管理");
          }
    }

    mod congress {
        pub fn legislate() {
}
    }
   
    mod court {
        fn judicial() {
            super::congress::legislate();
        }
    }
}*/

/*mod back_of_house {
    pub struct Breakfast {
        pub toast: String,
        seasonal_fruit: String,
    }

    impl Breakfast {
        pub fn summer(toast: &str) -> Breakfast {
            Breakfast {
                toast: String::from(toast),
                seasonal_fruit: String::from("peaches"),
            }
        }
    }
}

pub fn eat_at_restaurant() {
    let mut meal = back_of_house::Breakfast::summer("Rye");
    meal.toast = String::from("Wheat");
    println!("I'd like {} toast please", meal.toast);
}*/

fn main() {
     //nation::government::govern();

     //eat_at_restaurant()
     
     println!("{}", (PI / 2.0).sin());
}
